Study of Positronium formation in nano-channelled silicon as a function of sample temperature

16th International Conference on Positron Annihilation

Mariazzi, S.^1 ; Dinoto, L.^1 ; Ravelli, L.^2 ; Egger, W.^2 ; Brusa, R.S.^1

Dipartimento di Fisica, Università di Trento and INFN, Gruppo Collegato di Trento, Via Sommarive 14, I-38123 Povo, Trento, Italy^1

Institut für Angewandte Physik und Messtechnik, Universität der Bunderswehr München, 85577 Neubiberg, Germany^2

关键词: Nano channels;    Positive charge distribution;    Positron annihilation spectroscopy (PAS);    Positronium formation;    Ps formations;    Sample temperature;    Si/SiO2 interface;    Temperature range;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/443/1/012061/pdf
DOI  :  10.1088/1742-6596/443/1/012061

来源: IOP

【 摘 要 】

Oxidized nanochannel in silicon have been demonstrated to be suitable for positronium (Ps) formation and cooling also at low sample temperature. To investigate the Ps yield and to clarify the Ps formation mechanism we studied, by Positron Annihilation Spectroscopy (PAS), nanochanneled Si p-type samples in the 150-430 K temperature range. Ps yield was found to be constant in the 150-300 K temperature range, then it increases up to ∼50% of its value from 350-400 K. This effect is associated to a decrease of the fraction of positrons annihilating in Si and in the SiO2layer on the nanochannels surface. This finding is compatible with the thermal decrease of the positive charge distribution at the Si/SiO2interface limiting e+reaching the SiO2layer and to a charge rearrangement at the SiO2surfaces.